Al—Si corrosion protection coatings

Abstract

The invention relates to a layer system coated on a substrate, the layer system comprising a functional layer and an intermediate layer, the intermediate layer being disposed between the substrate and the functional layer, the functional layer comprising both the elements aluminum and silicon but not necessarily in elemental form, and the functional layer comprising oxygen or nitrogen or both, characterized in that the intermediate layer comprises, measured in at %, percent more silicon and/or percent more aluminum than the functional layer.

The invention claimed is: 
     
         1 . A layer system coated on a substrate, the layer system comprising a functional layer and an intermediate layer, the intermediate layer being disposed between the substrate and the functional layer, the functional layer comprising both the elements aluminum and silicon but not necessarily in elemental form, and the functional layer comprising oxygen or nitrogen or both, wherein the intermediate layer comprises, measured in atomic percent, at least more silicon or more aluminum than the functional layer, wherein the functional layer is a multi-layered layer and at least the Al/Si ratio or the O/N ratio change at least periodically over at least part of the layer thickness or aperiodically over at least part of the layer thickness. 
     
     
         2 . The layer system according to  claim 1 , wherein the intermediate layer is a layer system which comprises silicon and aluminum and which may additionally also comprise at least one further element from the material of the substrate. 
     
     
         3 . The layer system according to  claim 1 , wherein the functional layer comprises, in addition to at least the elements Al, Si, O or N, other elements, if any, only as at least doping or impurity. 
     
     
         4 . The layer system according to  claim 1 , wherein the functional layer is a mono-layered layer or a multi-layered layer. 
     
     
         5 . The layer system according to  claim 1 , wherein the ratio of Al to Si (Al/Si) atoms in the functional layer is between 2 and 5. 
     
     
         6 . The layer system according to  claim 1 , wherein the functional layer comprises Al droplets which are present in the layer in the as-deposited state and which contribute to diffusion processes and to the formation of mullite structures during the aging process. 
     
     
         7 . A layer system coated on a substrate, the layer system comprising a functional layer and an intermediate layer, the intermediate layer being disposed between the substrate and the functional layer, the functional layer comprising both the elements aluminum and silicon but not necessarily in elemental form, and the functional layer comprising oxygen or nitrogen or both, wherein the intermediate layer comprises, measured in atomic percent, at least more silicon or more aluminum than the functional layer, wherein the intermediate layer comprises, in addition to the elements Al and Si, elements, if any, only as at least doping or impurity or comprises one or more group elements of the group comprising of: metal of the substrate material, Si—O, Si—N, Si—O—N, Al—O, Al—N, Al—O—N.